Page 1 of 1

Tiny Speedboat Build

Posted: Mon Apr 25, 2022 4:36 pm
by Jetdriver69
Hey all, new to the forum and to boat building. I just finished modifying to a great extent a PowerWheels Dodge Viper for my small grandson and was looking for a new project.

I saw youtube videos of a father in Australia who designed a very small, weedeater motor powered speedboat for his 4 year old grandson and thought what the heck, that would work.
Tiny-Motorboat.jpg
Tiny-Motorboat.jpg (46.92 KiB) Viewed 4333 times
So as I was sitting in a hotel room on the beach in Santa Monica last November, I designed a 6.5 ft foam, wood and fiberglass mini cigarette boat powered by a Zenoah 320 4.5 hp RC boat motor coupled to a 3D printed 70mm jet drive.

The first picture is the pile of foam and wood I started with.
IMG_1526.jpg
IMG_1526.jpg (77.18 KiB) Viewed 4333 times
These next two photos are after cutting the sections of foam out with a hot wire and glueing them together.
IMG_1693.jpg
IMG_1693.jpg (86.12 KiB) Viewed 4333 times
IMG_1679.jpg
IMG_1679.jpg (71.68 KiB) Viewed 4333 times
Yes I know using this type of foam isnt the best for structural integrity and in hindsight, should have made the boat out of wood entirely. But after 3 layers of epoxy and fiberglass boat cloth and a whole bunch of epoxy thickened fillets in the joints, the boats looks pretty rigid for its use in a very calm pond or lake setting. Besides the kid is only so small for so long.

I'm just about done with the boat so I can post a few pictures a day until I catch up with the actual progress.

Re: Tiny Speedboat Build

Posted: Mon Apr 25, 2022 9:36 pm
by Fuzz
That is a great project! Grand dad..............lean, mean, spoiling machine :D That is the best thing about grand kids, at least that is what I am told. Please post as you can and show the process to us.

Re: Tiny Speedboat Build

Posted: Tue Apr 26, 2022 9:38 am
by Jetdriver69
In order to move the CG a little toward center in the boat, I wanted to move the engine and jet drive a bit forward.
So I made a spacer for the water outlet out of pine which will be fully encapsulated with epoxy resin.
IMG_1700.jpg
IMG_1700.jpg (89.34 KiB) Viewed 4295 times
IMG_1697.jpg
IMG_1697.jpg (74.19 KiB) Viewed 4295 times
Attaching outside battens to the boat
IMG_1695.jpg
IMG_1695.jpg (101.84 KiB) Viewed 4295 times
IMG_1694.jpg
IMG_1694.jpg (100.12 KiB) Viewed 4295 times

Re: Tiny Speedboat Build

Posted: Wed Apr 27, 2022 1:53 am
by Fuzz
Enjoying seeing this :wink:

Re: Tiny Speedboat Build

Posted: Wed Apr 27, 2022 6:17 am
by cape man
Too cool!!

Re: Tiny Speedboat Build

Posted: Wed Apr 27, 2022 7:12 am
by jbo_c
I think these are great and look like fun. Most of the ones I’ve seen seem to be a tighter fit than I’d be comfortable with from a safety standpoint. Make sure you leave plenty of unobstructed space to slide out in the event of capsize.

Jbo

Re: Tiny Speedboat Build

Posted: Wed Apr 27, 2022 8:45 am
by Jetdriver69
Thanks for the comments. Yes leaving plenty of space to get out but the boat is pretty wide compared to the length so it should be fairly stable

I skinned the hull with foam sheets using clamps, screw blocks and marine adhesive.
IMG_1714.jpg
IMG_1714.jpg (84.62 KiB) Viewed 4242 times
Filled in the keel voids with expanding foam
IMG_1715.jpg
IMG_1715.jpg (82.91 KiB) Viewed 4242 times
Used epoxy body filler to fill in the seams and filled the bow section with contoured pieces of the foam
IMG_1724.jpg
IMG_1724.jpg (72.21 KiB) Viewed 4242 times

Re: Tiny Speedboat Build

Posted: Thu Apr 28, 2022 8:35 am
by Jetdriver69
To get the proper shape of the bow, I used thinner strips of foam glued vertically.
IMG_1730.jpg
IMG_1730.jpg (73.88 KiB) Viewed 4194 times
In places I couldn't clamp or use screw blocks, I used sharpened wooden sticks to keep the foam in place while the glue dried.
IMG_1731.jpg
IMG_1731.jpg (79.05 KiB) Viewed 4194 times
After all was dried, I used a knife to trim away the excess.
IMG_1744.jpg
IMG_1744.jpg (64.49 KiB) Viewed 4194 times

Re: Tiny Speedboat Build

Posted: Fri Apr 29, 2022 1:50 pm
by Jetdriver69
I glued thin plywood to the foam battens for a bit more protection
IMG_1760.jpg
IMG_1760.jpg (89.18 KiB) Viewed 4136 times
IMG_1763.jpg
IMG_1763.jpg (111.15 KiB) Viewed 4136 times
I made a trailer out of PVC pipe and wheels from Harbor Freight
IMG_1770.jpg
IMG_1770.jpg (102.45 KiB) Viewed 4136 times
Dry fitting the decking before cutting out the engine and cockpoit openings
IMG_1758.jpg
IMG_1758.jpg (94.26 KiB) Viewed 4136 times

Re: Tiny Speedboat Build

Posted: Fri Apr 29, 2022 2:43 pm
by narfi
Very nice!
You sure grandpa or dad aren't going to feel they need to try it first and swamp it before the little guy gets a chance in it?........
Can't wait to watch the rest of your progress!!!

Re: Tiny Speedboat Build

Posted: Fri Apr 29, 2022 4:35 pm
by Jetdriver69
Might stick my wife in it poolside to check everything.

She is 4'11 and about 95 lbs.

Re: Tiny Speedboat Build

Posted: Sat Apr 30, 2022 8:58 pm
by Jetdriver69
Dry fitting the engine mounting plate with the jet drive
IMG_1796.jpg
IMG_1796.jpg (105.63 KiB) Viewed 27024 times
Mocking up the space needed for the engine
IMG_1797.jpg
IMG_1797.jpg (84.68 KiB) Viewed 27024 times
Mocking up the seating and flooring
IMG_1798.jpg
IMG_1798.jpg (97.16 KiB) Viewed 27024 times
Glued in a wood header for screwing down the decking, windshield frame and the cleat
IMG_1800.jpg
IMG_1800.jpg (110.11 KiB) Viewed 27024 times

Re: Tiny Speedboat Build

Posted: Sun May 01, 2022 9:37 am
by Jetdriver69
Not sure if it will help getting the boat on plane, but adding lifting strakes to the hull.
IMG_1803.jpg
IMG_1803.jpg (101.1 KiB) Viewed 27006 times
After a bit of research and considering the simplicity, I just used half round wood moulding pieces.
I drilled through the foam hull and block glued them in place.
IMG_1804.jpg
IMG_1804.jpg (106.8 KiB) Viewed 27006 times
Will seal the holes with thickened epoxy resin and the outer hull will have 3 layers of boat cloth with epoxy resin.
IMG_1805.jpg
IMG_1805.jpg (98.81 KiB) Viewed 27006 times

Re: Tiny Speedboat Build

Posted: Sun May 01, 2022 3:09 pm
by Jetdriver69
Dry fitting the deck after cutting out the engine access and cockpit opening.
IMG_1807.jpg
IMG_1807.jpg (102.31 KiB) Viewed 26992 times
IMG_1808.jpg
IMG_1808.jpg (128.77 KiB) Viewed 26992 times

Re: Tiny Speedboat Build

Posted: Mon May 02, 2022 10:35 am
by Jetdriver69
Dry fitting the engine and jet drive
IMG_1815.jpg
IMG_1815.jpg (93.56 KiB) Viewed 26972 times
With the very long two stroke racing exhaust included.
I added a wooden frame so I would have a hardpoint for screws when I installed the decking
IMG_1816.jpg
IMG_1816.jpg (126.71 KiB) Viewed 26972 times
Checking clearance with the decking in place.
Surprising it all works
IMG_1819.jpg
IMG_1819.jpg (109.16 KiB) Viewed 26972 times

Re: Tiny Speedboat Build

Posted: Mon May 02, 2022 2:42 pm
by VT_Jeff
Legend!

Re: Tiny Speedboat Build

Posted: Mon May 02, 2022 5:41 pm
by Jetdriver69
Temporarily block scewed down the deck and dry fitted the windscreen and side rails.
IMG_1820.jpg
IMG_1820.jpg (109.97 KiB) Viewed 26951 times
I eventually made the windscreen a bit taller
IMG_1821.jpg
IMG_1821.jpg (127.49 KiB) Viewed 26951 times
I cut out retractable spring handles into the battens for easier lifting.
IMG_1822.jpg
IMG_1822.jpg (110.19 KiB) Viewed 26951 times

Re: Tiny Speedboat Build

Posted: Mon May 02, 2022 11:21 pm
by Jetdriver69
Mocking up the steering assembly.
I eventually used a 1/4 steel cable inside clear plastic tubing filled with lube and eyelets pressed into the ends.
IMG_1825.jpg
IMG_1825.jpg (110.59 KiB) Viewed 26938 times
Attached that to some RC boat push/pull hardware so when you move the handle bars left and right the cable moves the jet drive steering.
IMG_1826.jpg
IMG_1826.jpg (107.07 KiB) Viewed 26938 times
Eventually cut down the handle bars smaller and painted blue to match the boat color.
The wooden housing forward of the handle bars was supposed to be the location for a digital 2 stroke tach.
But the cable wasnt long enough and it was impossible to splice. So I removed the housing and mounted the tach in the engine bay.
IMG_1845.jpg
IMG_1845.jpg (94.87 KiB) Viewed 26938 times
Dry fitting the larger windscreeen which I eventually used.
IMG_1847.jpg
IMG_1847.jpg (93.39 KiB) Viewed 26938 times

Re: Tiny Speedboat Build

Posted: Tue May 03, 2022 9:09 am
by VT_Jeff
Any thoughts of popping a quick mold off of that hull/deck?

Re: Tiny Speedboat Build

Posted: Tue May 03, 2022 9:35 am
by Dougster
This is a fascinating build and I check it daily. Thanks for sharing.

Dougster

Re: Tiny Speedboat Build

Posted: Wed May 04, 2022 5:08 pm
by Jetdriver69
I was asked to use it as a mold previously but too much of a PITA.

Its definitely a one off.

I'm actually working so no posts for a couple of days but I have lots of pictures left.

I'm just about ready to hook up the engine controls and stick it in the pool so the post pictures are months behind.

Re: Tiny Speedboat Build

Posted: Thu May 05, 2022 8:50 am
by Browndog
Fun build thread to follow.

Well done!

Building a boat, especially one that will likely be outgrown, for a family member is really a gift of love and labor. Creating something unique and building lasting memories along the way for both you and them.

Documenting it for the forum is a gift to all of us. Thank you.

I can imagine already an RB 16 in the future for when the little guy gets a little bigger.

Re: Tiny Speedboat Build

Posted: Thu May 05, 2022 2:11 pm
by Jetdriver69
I actually like the Glen L Dynojet.
Stitch n glue construction mated to a recycled jet ski motor and drive.
But that’s way off.

Re: Tiny Speedboat Build

Posted: Thu May 05, 2022 5:50 pm
by Jetdriver69
Dry fitting jet drive steering
IMG_1851.jpg
IMG_1851.jpg (103.54 KiB) Viewed 38869 times
IMG_1852.jpg
IMG_1852.jpg (123.4 KiB) Viewed 38869 times
I finished the motor mount. Then will coat with epoxy resin and paint blue.
IMG_1855.jpg
IMG_1855.jpg (93.32 KiB) Viewed 38869 times
I replaced the 3D printed impeller with metal version.
Supposedly it is much more efficient.
IMG_1868.jpg
IMG_1868.jpg (75.02 KiB) Viewed 38869 times

Re: Tiny Speedboat Build

Posted: Sat May 07, 2022 9:02 am
by Jetdriver69
After adding thickened epoxy to all the interior joints and fiberglassing the interior foam with epoxy and 6 ounce boat cloth, I dry fitted the cockpit interior panels to hide it all.
Eventually I will fill the voids with expanding foam and fiberglass all the exposed wood.
IMG_1869.jpg
IMG_1869.jpg (116.69 KiB) Viewed 38836 times
IMG_1870.jpg
IMG_1870.jpg (96.61 KiB) Viewed 38836 times

Re: Tiny Speedboat Build

Posted: Sat May 07, 2022 6:53 pm
by Jetdriver69
Screwed down the decking and attached the instrument panel and windscreen frame.
IMG_1894.jpg
IMG_1894.jpg (120.24 KiB) Viewed 38823 times
Filled in all the screw holes with thickened epoxy and spread a layer of epoxy over the deck and sides.
IMG_1908.jpg
IMG_1908.jpg (114.59 KiB) Viewed 38823 times

Re: Tiny Speedboat Build

Posted: Sat May 07, 2022 7:00 pm
by Jetdriver69
Spreading the first layer of 6 oz boat cloth.
IMG_1879.jpg
IMG_1879.jpg (80.42 KiB) Viewed 38821 times
Didn't have enought left on the roll so I had to patch it.
IMG_1880.jpg
IMG_1880.jpg (66.66 KiB) Viewed 38821 times
Layer of 4 oz boat cloth.
IMG_1882.jpg
IMG_1882.jpg (63.87 KiB) Viewed 38821 times
After multiple coats of epoxy resin and trimming the excess cloth. That stuff is messy but at least it doesnt stink.
IMG_1884.jpg
IMG_1884.jpg (76.89 KiB) Viewed 38821 times
After letting the epoxy cure for 3 days, a good sanding with 60-80 grit.
IMG_1893.jpg
IMG_1893.jpg (93.24 KiB) Viewed 38821 times

Re: Tiny Speedboat Build

Posted: Tue May 10, 2022 8:42 am
by Jetdriver69
The finished motor mount plate. That just gets screwed and glued into the wood/fiberglass floor.
The blue boxy looking thing is a route for the the sterring cable
IMG_1910.jpg
IMG_1910.jpg (86.32 KiB) Viewed 38766 times
The 3D printed 70mm jetdrive and steering. Surprising good quality coming from China.
IMG_1911.jpg
IMG_1911.jpg (108.02 KiB) Viewed 38766 times
The steering system I came up with.
Eseentially a 1/4 inch steel cable inside a lubed clear tube.
IMG_1923.jpg
IMG_1923.jpg (134.87 KiB) Viewed 38766 times
The cable ends have eyes attached which connect to RC boat push/pull rods.
I made a 1/4 wood circle which routes the cable into the sidewalls and secures it in place with zip ties.
IMG_1924.jpg
IMG_1924.jpg (141.24 KiB) Viewed 38766 times
Surprising it works really well and infinetly cheaper than trying to source a correct length boat steering cable.
IMG_1925.jpg
IMG_1925.jpg (108.38 KiB) Viewed 38766 times

Re: Tiny Speedboat Build

Posted: Tue May 10, 2022 8:51 am
by Jetdriver69
Routing the steering cable, throttle cable and kill switch cable down through the sidewall and back through the rear bulkhead to the engine bay.
IMG_1927.jpg
IMG_1927.jpg (110.67 KiB) Viewed 38765 times
Eventually I will cover the voids with fiberglassed plywood to hide everything, glass some thin plywood onto the foam walls for better puncture protection and shoot expanding foam in the dead spaces.
IMG_1928.jpg
IMG_1928.jpg (99.32 KiB) Viewed 38765 times
That liitle box on top of the glare shield was supposed to be a housing for a 2 stroke tach, but the cable was just too short to make it back to the engine.
So I eventually moved it to the engine bay. Like a 3 year old is going to watch rpms anyway.
IMG_1929.jpg
IMG_1929.jpg (117.34 KiB) Viewed 38765 times

Re: Tiny Speedboat Build

Posted: Wed May 11, 2022 8:03 am
by Jetdriver69
Starting the deck fiberglassing.
IMG_1932.jpg
IMG_1932.jpg (104.39 KiB) Viewed 38734 times
I spread a layer of epoxy resin over the raw wood to encapsulate then put 4 oz boat cloth over that.
IMG_1933.jpg
IMG_1933.jpg (100.19 KiB) Viewed 38734 times
After letting it cure for a couple of hours, I trimmed the cloth at the tape lines and let it sit for 3 days.
IMG_1935.jpg
IMG_1935.jpg (107.98 KiB) Viewed 38734 times
IMG_1936.jpg
IMG_1936.jpg (108.69 KiB) Viewed 38734 times
Not a great picture, but fiberglassing the transom. I later trimmed at the tape lines which were the overlap from the hull fiberglassing.
Actually came out decent for my first time at fiberglassing until I discovered how much sanding, void repairs and filling was later to come.
IMG_1931.jpg
IMG_1931.jpg (94.98 KiB) Viewed 38734 times

Re: Tiny Speedboat Build

Posted: Wed May 11, 2022 9:30 pm
by Jetdriver69
Spread a coat of Total Boat Fairing compound over the sanded fiberglass top and bottom.
The first of many coats
IMG_1964.jpg
IMG_1964.jpg (80.58 KiB) Viewed 33077 times
IMG_1966.jpg
IMG_1966.jpg (78.27 KiB) Viewed 33077 times
IMG_1970.jpg
IMG_1970.jpg (98 KiB) Viewed 33077 times
After sanding down the fairing to eliminate high spots, I got to work identifying air voids in the glass.
Nothing to do but circle them with a marker, use a dremel to cut them out and bevel the hole and fill with epoxy resin thickened with microballons.
IMG_1989.jpg
IMG_1989.jpg (89.28 KiB) Viewed 33077 times
Yes I had to do this more than once. I think I will stick to wood from now on...
IMG_1990.jpg
IMG_1990.jpg (96.95 KiB) Viewed 33077 times

Re: Tiny Speedboat Build

Posted: Thu May 12, 2022 12:27 am
by narfi
Practice makes (closer to) perfect!!!

Re: Tiny Speedboat Build

Posted: Thu May 12, 2022 10:15 pm
by Jetdriver69
Now for something different. Making bezels for fake instruments out of thin ply.
IMG_1991.jpg
IMG_1991.jpg (131.99 KiB) Viewed 33046 times
Bezels cut out, epoxy coated and primed.
IMG_2009.jpg
IMG_2009.jpg (124.48 KiB) Viewed 33046 times
Sprayed silver and cleared
IMG_2012.jpg
IMG_2012.jpg (149.14 KiB) Viewed 33046 times
The instrument stickers I got off a kids electric car website.
IMG_2065.jpg
IMG_2065.jpg (77.08 KiB) Viewed 33046 times
The engine bay deck lid with air scoop glassed in.
The open slots will be for chrome marine air louvers.
IMG_2008.jpg
IMG_2008.jpg (108.84 KiB) Viewed 33046 times

Re: Tiny Speedboat Build

Posted: Sun May 15, 2022 1:26 pm
by Jetdriver69
After fixing all the air voids, spreading another coat of fairing compound and sanding down through 400 grit, I shot a couple of cpats of primer.
IMG_2075.jpg
IMG_2075.jpg (86.04 KiB) Viewed 32974 times
Let me primer cure, then I will shoot the hull bottom with gloss white.
IMG_2077.jpg
IMG_2077.jpg (95.08 KiB) Viewed 32974 times
IMG_2099.jpg
IMG_2099.jpg (69.73 KiB) Viewed 32974 times

Re: Tiny Speedboat Build

Posted: Sun May 15, 2022 2:49 pm
by cape man
Who's your Grandaddy? 8)

Re: Tiny Speedboat Build

Posted: Sun May 15, 2022 3:04 pm
by Jetdriver69
I thought I was done and ready for paint, but i found more air voids and fixed those.
Then I thought the keel needed more protection so I glassed in some aluminum angle that I heated and bent to shape and cut into sections.
Epoxyed that to the keel and glassed over.
IMG_2108.jpg
IMG_2108.jpg (110.01 KiB) Viewed 32956 times
Then I decided since I had more aluminum angle to add that to the stern corners.
Epoxyed those down as it was only fiberglass and foam on the corners.
IMG_2145.jpg
IMG_2145.jpg (65.16 KiB) Viewed 32956 times
IMG_2146.jpg
IMG_2146.jpg (66.71 KiB) Viewed 32956 times

Re: Tiny Speedboat Build

Posted: Mon May 16, 2022 9:35 am
by Jetdriver69
I installed epoxy covered plywood inserts to hide the framing and filled the voids with expanding foam.
IMG_2194.jpg
IMG_2194.jpg (87.8 KiB) Viewed 32935 times
Will eventually fiberglass over the wood with 4 oz boat cloth and cover with a textured bed liner spray.
IMG_2195.jpg
IMG_2195.jpg (64.53 KiB) Viewed 32935 times
Finally fixed all the air voids, sanded down once again and re primed again.
Real painting is next.
IMG_2230.jpg
IMG_2230.jpg (76.04 KiB) Viewed 32935 times

Re: Tiny Speedboat Build

Posted: Mon May 16, 2022 9:42 am
by Dougster
Sure looks good. I like the angle iron touch. I have never tried to heat, bend and epoxy it though. Pretty sure I'd make a mess of it :roll:

Dougster

Re: Tiny Speedboat Build

Posted: Mon May 16, 2022 11:44 am
by Jetdriver69
Yes it wasnt easy.

I had to cut some scrap pine in the same curve line as the keel.

Then use a torch to heat the aluminum up and beat it to shape over the form.

Even then I couldnt get it bend as much as I needed, so I cut up the angle piece and fitted it to the keel one piece at a time.

Marine epoxied it in place, the fiberglass over that. If it comes off after all that then I quit.

Re: Tiny Speedboat Build

Posted: Mon May 16, 2022 2:02 pm
by Jetdriver69
Shot mulitple coats of gloss white. Then let it cure for 3 days and start laying down the tape for the blue stripes.
IMG_2259.jpg
IMG_2259.jpg (83.92 KiB) Viewed 32916 times
After the blue, I will spray it with an automotive high gloss clear with hardener.
IMG_2260.jpg
IMG_2260.jpg (70.54 KiB) Viewed 32916 times

Re: Tiny Speedboat Build

Posted: Tue May 17, 2022 11:06 am
by mhd
Looks great! Nice job!!!

Re: Tiny Speedboat Build

Posted: Tue May 17, 2022 11:36 am
by Jeff
Nice work!!! Jeff

Re: Tiny Speedboat Build

Posted: Fri May 20, 2022 10:20 am
by Jetdriver69
Taped off the areas to be painted Royal Blue
IMG_2269.jpg
IMG_2269.jpg (90.25 KiB) Viewed 25441 times
Taped in the masking
IMG_2271.jpg
IMG_2271.jpg (112.03 KiB) Viewed 25441 times
First of a couple of coats of blue.
IMG_2273.jpg
IMG_2273.jpg (94.92 KiB) Viewed 25441 times
After curing and masking removal. This is rattle can gloss paint and it flowed pretty good.
Adding the clear automotive clear with hardener really made it shine.
Then a wet sand, buff out with compound and wax.
IMG_2276.jpg
IMG_2276.jpg (84.02 KiB) Viewed 25441 times

Re: Tiny Speedboat Build

Posted: Fri May 20, 2022 11:56 am
by Dougster
So cool. I can't get over all the things you can do so well. Depending on my mood, it's either intimidation or inspiring 8O

Dougster

Re: Tiny Speedboat Build

Posted: Fri May 20, 2022 12:38 pm
by Jetdriver69
I made a boat trailer of of PVC pipe and cheap Harbor Freight wheels and castors.
IMG_2463.jpg
IMG_2463.jpg (130.92 KiB) Viewed 25420 times
Used pipe isolation to cushion the keel and marine carpet on the rear supports
IMG_2464.jpg
IMG_2464.jpg (135.13 KiB) Viewed 25420 times
The engine deck lid painted with Royal Blue and racing stripes.
IMG_2440.jpg
IMG_2440.jpg (95.21 KiB) Viewed 25420 times
I bought one long marine louver vent off eBay and cut it up to fit both holes
IMG_2441.jpg
IMG_2441.jpg (99.83 KiB) Viewed 25420 times
The underside of the engine lid with decals. Will shoot automotive gloss clear over eventually.
IMG_2442.jpg
IMG_2442.jpg (86.56 KiB) Viewed 25420 times

Re: Tiny Speedboat Build

Posted: Fri May 20, 2022 6:52 pm
by OrangeQuest
Looking very sharp but the vents are not correct. One needs to be reversed so one draws in air and the other vents it. Otherwise, not a lot of air will go in.

Re: Tiny Speedboat Build

Posted: Fri May 20, 2022 9:11 pm
by Jetdriver69
The hood scoop draws the air in, the louvers lets the air out.

Re: Tiny Speedboat Build

Posted: Sat May 21, 2022 5:59 am
by OrangeQuest
Jetdriver69 wrote: Fri May 20, 2022 9:11 pm The hood scoop draws the air in, the louvers lets the air out.
Oh!! Opps! I had to look twice. :oops:

Re: Tiny Speedboat Build

Posted: Sat May 21, 2022 7:19 am
by Jetdriver69
No worries.

This entire project was a “I’m just making this up as I go”. Had to redesign things more than once and a few things I wish I would have done differently but that’s how prototypes go.

Re: Tiny Speedboat Build

Posted: Sat May 21, 2022 11:33 am
by Jetdriver69
I added some rub strips on the flat part of the hull.
Will use the same strips to wrap around the deck for some rub protection.
You can really see the glossyness of the automotive clear with hardener.
Pricey spray can but works good.
IMG_2467.jpg
IMG_2467.jpg (86 KiB) Viewed 25350 times
Sanded out and ready for primer
IMG_2470.jpg
IMG_2470.jpg (104.93 KiB) Viewed 25350 times
Masked out and primed
IMG_2474.jpg
IMG_2474.jpg (77.09 KiB) Viewed 25350 times
Top coat of Royal Blue.
The windscreen and sides will be gloss black and have two white racing stripes down the middle of the deck.
IMG_2479.jpg
IMG_2479.jpg (92.91 KiB) Viewed 25350 times

Re: Tiny Speedboat Build

Posted: Sat May 21, 2022 4:57 pm
by cape man
I'm intimidated... 8)

Re: Tiny Speedboat Build

Posted: Sat May 21, 2022 7:19 pm
by Jetdriver69
I've been screwing around with this boat for a year and a half.

Starting from scratch with zero plans and no experience can make for a long project.

But throwing the boat in the pool tonight with kid installed to check for leaks and to see how low it sits.

I'm actaully way ahead of the picture progress.

Re: Tiny Speedboat Build

Posted: Sun May 22, 2022 4:53 am
by OrangeQuest
Been an interesting project to follow. And the results are amazing!

Re: Tiny Speedboat Build

Posted: Sun May 22, 2022 5:47 am
by Browndog
As I’ve commented before, this is a fun build to follow.

Looking forward to more posts and pictures of the finished project.

Re: Tiny Speedboat Build

Posted: Sun May 22, 2022 7:50 am
by Jetdriver69
Painted the racing stripes
IMG_2487.jpg
IMG_2487.jpg (105.14 KiB) Viewed 10150 times
The Zenoah decals are from the Japanese engine manufacturer.
A whole 32 cc and supposedly 4.5 hp at 14,000 rpms.
A top quality engine, much better than the Chinese knockoffs.
IMG_2488.jpg
IMG_2488.jpg (110.67 KiB) Viewed 10150 times
Masked off and shot the the gloss black for the windscreen and side rails
IMG_2490.jpg
IMG_2490.jpg (113.31 KiB) Viewed 10150 times
Now let it cure and shoot the clear.
IMG_2492.jpg
IMG_2492.jpg (92.13 KiB) Viewed 10150 times

Re: Tiny Speedboat Build

Posted: Sun May 22, 2022 1:09 pm
by Jetdriver69
Got to work for a couple of days starting Monday so I thought Id post another round of pictures.
Installed the boat name, vinyl lettering off eBay for cheap.
IMG_2494.jpg
IMG_2494.jpg (85.25 KiB) Viewed 10127 times
Made the boat into a mini cigarette theme.
IMG_2497.jpg
IMG_2497.jpg (104.77 KiB) Viewed 10127 times
Will shoot a layer of gloss clear over the decals.
IMG_2498.jpg
IMG_2498.jpg (112.84 KiB) Viewed 10127 times

Re: Tiny Speedboat Build

Posted: Sun May 22, 2022 1:17 pm
by Jetdriver69
A question for the builder experts, which I am not.

I put the boat in the pool last night with a 35 lb kid at the helm, but with no fuel tank or fuel weight.

The boat is super stable. I rocked it left and right pretty aggressively to the cockpit splash guard and it righted itself immediately with zero water getting in.

However the bow seems to be a little lower than the stern. But the jet drive outlet looks to be at the perfect level, just barely covered to the top of the outlet lip by the pool water.

Should I try adding ballast to the far aft of the engine bay to get the nose up or will the bow dig in under power application without it?

I did install lifting strakes assuming the boat can get fast enough to get on plane.

Thanks

Re: Tiny Speedboat Build

Posted: Sun May 22, 2022 3:00 pm
by cape man
Bring some water jugs or sand bags for the launch.

Re: Tiny Speedboat Build

Posted: Sun May 22, 2022 7:08 pm
by Jetdriver69
We got some ankle weights that would work great just to see what amount of ballast would work.

Re: Tiny Speedboat Build

Posted: Wed May 25, 2022 1:44 pm
by Jetdriver69
Painted the instrument face blue and attached the fake gauges and dry fitted the kill switch
IMG_2499.jpg
IMG_2499.jpg (96.9 KiB) Viewed 10050 times
Extra instrument decals that came with the set, so I made 2 clusters that be be screwed into the left and right cockpit sidewalls.
IMG_2500.jpg
IMG_2500.jpg (127.24 KiB) Viewed 10050 times
I added a rubber matting on top of the plywood flooring. Then shot textured bedliner over that and painted a gloss black deck paint with hardener.
IMG_2517.jpg
IMG_2517.jpg (121.37 KiB) Viewed 10050 times
IMG_2518.jpg
IMG_2518.jpg (106.25 KiB) Viewed 10050 times

Re: Tiny Speedboat Build

Posted: Fri May 27, 2022 10:30 am
by Jetdriver69
Installed the jet drive. I aligned the holes before fiberglassing and used cut down threaded stock with lock nuts on both ends
IMG_2561.jpg
IMG_2561.jpg (85.48 KiB) Viewed 4816 times
Installed the steering. The hole throught the hull will have rubber boots on both ends through a grease filled fitting I made.
Hopefully no leaks
IMG_2563.jpg
IMG_2563.jpg (76 KiB) Viewed 4816 times
Installed the pump and motor mount plate
IMG_2564.jpg
IMG_2564.jpg (86.87 KiB) Viewed 4816 times
Bolted down the engine and attached to the jet pump
Red wire is for the kill switch, clear tube is the steering and black wire is the throttle cable.
Still have to route the water cooling lines
IMG_2566.jpg
IMG_2566.jpg (118.93 KiB) Viewed 4816 times

Re: Tiny Speedboat Build

Posted: Fri May 27, 2022 12:03 pm
by cape man
I am so enjoying this one! Can't wait to see it running and floating!

Re: Tiny Speedboat Build

Posted: Fri May 27, 2022 11:13 pm
by Jetdriver69
Installed the sidewall instrument clusters and painted trim piece
IMG_2567.jpg
IMG_2567.jpg (106.45 KiB) Viewed 4792 times
The trim piece hides the opening cut to access the bolts that secure recessed handles on the battens
IMG_2568.jpg
IMG_2568.jpg (72.63 KiB) Viewed 4792 times
Installed an automotive door trim rub strip to help protect the finish
IMG_2569.jpg
IMG_2569.jpg (85.22 KiB) Viewed 4792 times
The trim had 3M tape attached but added small wood screws dipped in epoxy.
IMG_2570.jpg
IMG_2570.jpg (102.6 KiB) Viewed 4792 times
Covered the screw heads with clear and added the US flag on the stern
IMG_2571.jpg
IMG_2571.jpg (99.59 KiB) Viewed 4792 times

Re: Tiny Speedboat Build

Posted: Sat May 28, 2022 6:29 am
by cape man
You have to be really close!

Re: Tiny Speedboat Build

Posted: Sat May 28, 2022 9:01 am
by Dougster
Terrific looking build!

Dougster

Re: Tiny Speedboat Build

Posted: Sat May 28, 2022 9:46 am
by Jetdriver69
Still have to hook up the steering, throttle cable, kill switch and water cooling lines.

I’ve had it in the water to test for leaks but no run up yet.

Re: Tiny Speedboat Build

Posted: Sat May 28, 2022 7:10 pm
by Jetdriver69
Mounted the engine deck lid with chrome marine hinges and added two 10 lb hydraulic lifts.
IMG_2592.jpg
IMG_2592.jpg (97.85 KiB) Viewed 4743 times
Added the two stroke battery powered tachometer and hour meter.
Pretty simple and cheap, just wrap the lead around the spark plug cable.
IMG_2593.jpg
IMG_2593.jpg (59.73 KiB) Viewed 4743 times
I originally was going to use a go cart drifting seat with lawnmower sliding mounts.
But i didnt like the way it looked and the seat got in the way of opening the deck lid.
So I designed a simple seat out of plywood, foam and marine vinyl.
IMG_2605.jpg
IMG_2605.jpg (112.41 KiB) Viewed 4743 times

Re: Tiny Speedboat Build

Posted: Sun May 29, 2022 7:38 am
by cape man
If the kid has half the fun using it as you are building it... 8)

Re: Tiny Speedboat Build

Posted: Sun May 29, 2022 9:06 am
by Jetdriver69
If I didnt have to constantly redesign things or replace cheap Chinese parts I bought off Alibaba months ago.

I recently installed the twist grip throttle and it snapped in half the first time I used it.

I'm going for a large lawnmower type hand throttle on the side wall now.

That will be easier to ensure reduced power settings are used with a stop engineered in the housing somewhere.

Of course I will have to design that when it shows up in the mail.

Re: Tiny Speedboat Build

Posted: Sun May 29, 2022 9:26 am
by Jetdriver69
Installed and cut to length the exhaust.
Will have to tune it when the engine is running.
IMG_2631.jpg
IMG_2631.jpg (85.59 KiB) Viewed 4712 times
Used header heat wrap to protect the transom and used a RC boat exhaust support to keep it from vibrating too much.
IMG_2632.jpg
IMG_2632.jpg (81.01 KiB) Viewed 4712 times

Re: Tiny Speedboat Build

Posted: Mon May 30, 2022 6:37 pm
by Jetdriver69
My grandson very excited to get in the water
IMG_0165.jpg
IMG_0165.jpg (121.29 KiB) Viewed 3107 times
Seems very stable. I rocked it pretty aggressively it righted itself immediately.
IMG_0198.jpg
IMG_0198.jpg (91.66 KiB) Viewed 3107 times
I think the bow is a little lower than the stern but the jet pump outlet is at the perfect level.
No leaks, so that is good.
IMG_0193.jpg
IMG_0193.jpg (92.6 KiB) Viewed 3107 times
Not sure if I will have to add some aft ballast when the boat is under power. Thats the next test.
IMG_0191.jpg
IMG_0191.jpg (83.31 KiB) Viewed 3107 times

Re: Tiny Speedboat Build

Posted: Mon May 30, 2022 9:25 pm
by OrangeQuest
If you don't add ballast to the aft area, it will plow when he lets off the throttle and steer left or right. It will act like the stern is lifted by a wave and turn sharply and uncontrollable.

Re: Tiny Speedboat Build

Posted: Tue May 31, 2022 8:39 am
by Jetdriver69
Thanks for the input.

I’m going to test with two 5 lbs hand weights as far aft as possible and go from there.

Re: Tiny Speedboat Build

Posted: Wed Jun 01, 2022 2:22 pm
by Jetdriver69
Attached the steering cable to the RC boat push/pull rod.
IMG_2662.jpg
IMG_2662.jpg (91.08 KiB) Viewed 3048 times
The Steering bar gives full travel left and right, but I need to add some static stops to keep the kid from moving the bar too far.
IMG_2660.jpg
IMG_2660.jpg (121.92 KiB) Viewed 3048 times
Probably going to cut the steering bar down by about 1.5 inches each side to shorten the throw.
IMG_2659.jpg
IMG_2659.jpg (125.73 KiB) Viewed 3048 times

Re: Tiny Speedboat Build

Posted: Wed Jun 01, 2022 3:38 pm
by cape man
What's left? Fire that baby up!

Re: Tiny Speedboat Build

Posted: Wed Jun 01, 2022 4:39 pm
by Jetdriver69
Today I hooked up all the water cooling plumbing and drilled the holes for the inlets and exhaust.

Still need to install the gas tank and lines and kill switch.

Had to completley redesign the throttle. The cheap Chinese knock off twist grip snapped in half the first time I used it.

So bought a large steel lawnmower type hand throttle and made a housing for it for the right side of the cockpit. The epoxy is drying on the wood as I type.

Then paint royal blue and route the throttle line through the bulkhead.

Cut the handlebar control down by 1.5 inches on each side to reduce the throw necessary for full nozzle deflection.

Gots to work til the 7th, then off until the 30th. Flying to Cabo, yeah its rough.

It will be done before 30 June!

Re: Tiny Speedboat Build

Posted: Thu Jun 02, 2022 7:43 pm
by Matt Gent
This is awesome!

Re: Tiny Speedboat Build

Posted: Thu Jun 02, 2022 8:47 pm
by Jetdriver69
You guys are too kind.

Just a grandpa spoiling his only grandson.

Re: Tiny Speedboat Build

Posted: Tue Jun 07, 2022 5:06 pm
by Jetdriver69
Back from a trip for a couple of days then back out again for a while.
Drilled the hole in the transom for the water cooling inlet
IMG_2668.jpg
IMG_2668.jpg (57.2 KiB) Viewed 2939 times
And attached the supply line
IMG_2669.jpg
IMG_2669.jpg (61.87 KiB) Viewed 2939 times
Hooked up all the cooling supply and exhaust lines
IMG_2673.jpg
IMG_2673.jpg (97.08 KiB) Viewed 2939 times

Re: Tiny Speedboat Build

Posted: Wed Jun 08, 2022 2:15 pm
by Jetdriver69
Put the boat back in the pool with the kid onboard and 16 lbs of aft ballast.

Yes that makes a lot of difference in how the boat sits in the water.

I think im going to use exercise ankle weights that would be easily removed once the kid gets heavier.

When you add the 6 lbs for fuel and tank, it should be about right

Re: Tiny Speedboat Build

Posted: Tue Jun 14, 2022 3:36 pm
by Jetdriver69
Redesigned the throttle assembly as the cheap Chinese twist grip throttle broke the first time I used it.
So I bought a heavy duty lawn tractor hand throttle and made a wood housing covered with epoxy resin.
IMG_2703.jpg
IMG_2703.jpg (49.19 KiB) Viewed 2210 times
Dug out enough wood so the throttle can sit flush with a dremel
IMG_2704.jpg
IMG_2704.jpg (65.66 KiB) Viewed 2210 times
Screwed in place and workks very well and secure.
I havce a tiny Cigarette Racing Team decal coming that will fit between the screw heads.
IMG_2706.jpg
IMG_2706.jpg (113.84 KiB) Viewed 2210 times
I didnt like the look or the throw length of the bicycle handlebar steering so I made a yoke set up using thick walled PVC pipe.
IMG_2707.jpg
IMG_2707.jpg (107.44 KiB) Viewed 2210 times

Re: Tiny Speedboat Build

Posted: Fri Jun 17, 2022 3:23 pm
by Jetdriver69
Ran the throttle cable through the bulkhead and connected to the engine. Works great with full range of throttle movement.
Hooked up the dash mounted kill switch to the engine. The line was hidden through the dash and under the floor months ago.
IMG_2711.jpg
IMG_2711.jpg (112.38 KiB) Viewed 2178 times
The fuel tank finally arrived and dry fitted. The RC boat fuel lines should arrive this week sometime.
IMG_2709.jpg
IMG_2709.jpg (97.1 KiB) Viewed 2178 times
Showing the throttle connection, kill switch wiring to the coil and battery powered tachometer lead wrapped around the plug wire.
IMG_2710.jpg
IMG_2710.jpg (88.77 KiB) Viewed 2178 times
Hopefully run the fuel lines and fire this thing up when I get back from a trip.

Re: Tiny Speedboat Build

Posted: Fri Jun 17, 2022 3:48 pm
by Jetdriver69
Forgot this pix.
Installed the dash cover, easlily removed for steering maintenance if required.
IMG_2712.jpg
IMG_2712.jpg (109.7 KiB) Viewed 2173 times

Re: Tiny Speedboat Build

Posted: Fri Jul 01, 2022 10:56 pm
by Jetdriver69
Hooked up the 2.5L fuel tank to a shutoff valve and fuel filter
IMG_2728.jpg
IMG_2728.jpg (116.07 KiB) Viewed 2108 times
Then hooked the whole mess up to the carburetor.
The other yellow fuel line is for the primer bulb overflow. Just an old 35mm film case with an inlet nipple added on top.
If it doesnt storm tomorrow, we will try to fire this thing up.
IMG_2729.jpg
IMG_2729.jpg (85.83 KiB) Viewed 2108 times

Re: Tiny Speedboat Build

Posted: Sat Jul 02, 2022 9:17 am
by cape man
Drum roll.....

Re: Tiny Speedboat Build

Posted: Wed Jul 06, 2022 2:07 pm
by Jetdriver69
I had a devil of a time getting the RC boat engine to start.
Apparently these finicky little engine require a precise starting sequence or forget it.
No choke, very little prime, cover the velocity stack with your hand and slowly pull though once.
Then 1/4 throttle and a tiny shot of starting fliud and off it goes.
IMG_2733.PNG
The little engine is way more powerful than I thought. I dont doubt it could put out 4.3 hp at hight rpm's
Even at idle around 3800 rpm and directly connected to the jet drive it is putting a bit of thrust.
At 1/4 throttle it about pushed me over in the pool and at 1/2 throttle it tried to climb out of the pool.
Me thinks this thing will be much faster than I thought too. Wouldnt be surprised if it gets to 15 mph and should easily get on plane.
Going to have to mount an idle stop for when the kid gets on board...

Re: Tiny Speedboat Build

Posted: Thu Jul 07, 2022 6:35 am
by cape man
Awesome!

Re: Tiny Speedboat Build

Posted: Sun Jul 10, 2022 1:27 am
by BarraMan
I gotta say that I just love "Half Pint"! :D

Image

My only concern is will "the Kid" still fit in it once he completes the mechanical engineering degree required to operate it? 8O :doh: :help: :lol:

Re: Tiny Speedboat Build

Posted: Sun Jul 10, 2022 1:19 pm
by TomW1
BarraMan wrote: Sun Jul 10, 2022 1:27 am I gotta say that I just love "Half Pint"! :D

Image

My only concern is will "the Kid" still fit in it once he completes the mechanical engineering degree required to operate it? 8O :doh: :help: :lol:
What a great picture. You did a great job. :D Tom









w

Re: Tiny Speedboat Build

Posted: Mon Jul 11, 2022 4:06 pm
by Jetdriver69
Thanks for the comments

The kid is pretty smart and it will be tethered to me via the cleats with a long rope contraption I made.

Pretty much leaving it at idle and let him putt putt around until he gets a hang of it.

I still need to modify the exhaust a bit, fix a leak where the jet drive seals to the hull, adjust the idle and hook up the kill switch.

Maybe tomorrow and get it in the lake by this weekend unless I have to work.

Re: Tiny Speedboat Build

Posted: Mon Jul 11, 2022 4:41 pm
by cape man
Youtube!